part of part of smooth muscle cell sphincter associated smooth muscle cell A smooth muscle cell that is part of a sphincter. A sphincter is a typically circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. https://cellxgene.cziscience.com/cellguide/CL_0000358 Smooth muscle cells, as a broader category, are non-striated, involuntary muscle cells that usually exhibit contractions and dilation to facilitate numerous physiological functions. Sphincter associated smooth muscle cells are a specific type of smooth muscle cell that are primarily associated with the functioning of various anatomical sphincters in the human body. The traits that distinguishes sphincter associated smooth muscle cells from other smooth muscle cells are their location and specialized function in sphincter mechanisms. Sphincter associated smooth muscle cells play a pivotal role in regulating the opening and closure of the bodily sphincters. These sphincters can be found at multiple locations within the body including the gastrointestinal tract (namely the esophagus, stomach, small intestine, and rectum), the urinary tract, and the circulatory system. Upon receiving signals from the autonomous nervous system, these cells contract or relax to modulate the aperture of sphincters, thus controlling the movement of substances through them. Due to their precise and vital functional role, any dysfunction or dysregulation in these cells can lead to serious medical conditions, such as gastroesophageal reflux or urinary incontinence. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) sphincter muscle